Here's a fact for you. For most people, most of the time, the car is public transport. Ninety-two per cent of passenger travel takes place on the roads. The figure is higher if you exclude London, where the use of trains, buses and the tube is well above what you find beyond the capital and its environs.

It should immediately be clear how important the road network is to the economic and social fabric of the nation. The brutal truth is that for all the attention lavished on the railways, not least by politicians, it is a niche activity and will remain so – even if capacity is increased by a quarter, or a half, or even doubled. Anyway, significant expansion of the rail network is out of the question. Or at least it should be.

Why? Well, first because the country cannot afford it. It cannot afford to build extensive new rail infrastructure and, perhaps more importantly, it could not then afford to subsidise its running.

For all the legitimate moans from train commuters about the exorbitant cost of their journeys, they are still failing to pay their way. The taxpayer subsidises rail passengers to the tune of 21p per person per mile. By contrast, road users contribute a net 4p per mile to the Exchequer. You can see the problem. Not only do relatively few people travel on trains, they are only able to do so because others are digging deep into their pockets.

Two more quick things about train travel. First, around half of all train trips start or end in London. Second, train services do little to improve social cohesion. The 06.02 from Oxford to Paddington, and its ilk, are packed to the gunnels with the relatively well off, not those from the poorer sections of society. This latter group has instead been forced to turn to the car to get about: to go to the shops, get to work, take the children to school, visit loved ones in hospital – essentially, to have the same life chances as the rest of the population.

But what about buses? Well here, too, there is a price to be paid for the service they provide. Bus users cost taxpayers 6p per mile.

There are a number of rather obvious points to be made here – not least the fact that Souter's buses use the roads. The roads aren't the preserve of the personal automobile, though it might dominate. They are also home to Souter's vehicles – not to mention taxis, motorbikes, bicycles and virtually all of the country's commercial and freight traffic.

It should also be remembered that a lot of the money earmarked for roads is for maintenance, such as filling in potholes, and has nothing to do with the building of more motorways, bypasses, etc. The idea that the country is being steadily Tarmaced over is simply wrong. Road construction tailed off dramatically at the end of the 1990s. In 2008 there were 394,467 kilometres of road in Great Britain. That is just 1.5% more than a decade previously. Yet over the same period traffic rose by 11%. No surprise, then, that congestion has got so much worse.

The RAC Foundation is not blindly pro-car and anti-rail. It does not say roads good, railways bad. It does not see drivers as having any God-given right to be treated better than any other member of the travelling public. But by the same token we are against policies that ignore the facts and marginalise the masses. We support informed decision-making and economically sound judgements. To cut the roads budget yet further is neither.